* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
#header {
  display: flex;
  width: 320px;
  margin: 0 auto;
  padding: 20px;
}

#header div {
  margin-left: 30px;
  cursor: pointer;
  border-left: 2px solid transparent;
  border-right: 2px solid transparent;
}

.active {
  color: red;
  border-left: 2px solid transparent;
  border-right: 2px solid transparent;
  border-bottom: 2px red solid;
}
